Synthetic-color night vision

ABSTRACT

A synthetic color arrangement for a night vision inclusive surveillance system and its display is disclosed. The system partitions an input scene video signal into spectrally segregated scene components which are provided with separate processing as video signals and then recombined into a composite but now multiple color inclusive output representation of the input scene. The system in effect shifts input spectral components to a different part of the electromagnetic spectrum, the visible range of the spectrum, where operator controllable new spectral wavelength values are assigned to each different input scene spectral wavelength. Use of charge coupled device video camera elements, a video signal mixer apparatus, input wavelengths within both the visible and infrared spectral regions and signal processing according to the NTSC standards are also included. Military and non military uses of the apparatus are contemplated.

RIGHTS OF THE GOVERNMENT

The invention described herein may be manufactured and used by or forthe Government of the United States for all governmental purposeswithout the payment of any royalty.

BACKGROUND OF THE INVENTION

This invention concerns the field of color enhanced video displaysrelated to night vision devices.

It appears to be well recognized in the art of human communication thatcolor enhances the human ability to perceive patterns, remember shapes,and distinguish between otherwise similar shapes for examples. Perhapsone of the most outstanding present day examples of this humancharacteristic is to be found in the almost universal replacement ofmonochromatic image display equipment with the color enhancedcounterpart equipment in the fields of television reception and computerterminal devices. Indeed the consumer preferences which dictatemanufacturer's actions in these fields have limited the use ofmonochromatic equipment to special situations such as small sizeddisplays, low energy displays and other instances wherein response to aspecific need is considered to outweigh the benefits of a color image.These preferences also extend to the field of military equipmentdisplays, most notably for present purposes, to the field ofsurveillance equipment and especially to equipment involving fightvision capability, i.e., equipment involving night vision as a standalone capability or night vision in combination with day vision or withradar or laser sourced information.

In the field of night vision for example current state-of-the-artequipment provides intensified, monochromatic, shades-of-green imageryas an output to a user or observer. In general however, it is found thatcolor encoding can significantly increase observer performance withvisual tasks in this field just as color encoding is found to improvehuman performance and acceptance in the computer display and televisionfields. For present use purposes therefore it is considered to be aguiding principle that given an optimized night vision systemconfiguration, the visibility of certain man-made, natural, andcamouflaged objects, when color encoded, are rendered more visible tomost users; such color encoding thereby results in quicker objectdetection and/or recognition by a user or observer.

In addition to such color capable equipment being useful as a researchtool, night vision equipment of this color capability can also bepackaged for use as a vehicle-mounted night-sensor system for militaryand non military field use, for use in automotive equipment or aircraftfor example. Moreover color capable equipment which utilizes a broadspectrum of input wavelengths, wavelengths which include both thevisible and infrared (IR) spectral regions, can further increase systemand user-system performance. In this equipment, size and weight are notas critical as in the case of head-mounted vision systems sincecolor-capable equipment is viewed as having primary utility in largearea environments.

The U.S. Patent art indicates the presence of inventive activity in thefield of night vision devices and their testing. One such patent is U.S.Pat. No. 5,200,622 issued to J. M. Rouchon et al., a patent which isconcerned with an infrared observation system having a serf checkingfeature. The Rouchon patent uses a Narcissus effect parasitic imagewhich is imposed on the useful image of an aircraft pod mounted or otherinfrared system to achieve the self checking feature. The Rouchon patentappears however to be only distally related to the presentation ofartificially colored images in a system having infrared input capabilityas in the present invention.

The invention of R. D. Rosenthal in U.S. Pat. No. 5,204,532 is ofgeneral background interest with respect to the present invention in thesense that it discloses use of near infrared spectral calibrationstandards, i.e., spectral clusters of known calibration constant, toachieve accurate calibration of a blood glucose measuring system. TheRosenthal apparatus appears however to be only distally related to thepresentation of artificially colored images in a system having infraredinput capability as in the present invention.

Similarly the patent of J. R. Apperson et al., U.S. Pat. No. 5,206,511,is of general background interest with respect to the present invention.The Apperson patent discloses an arrangement for calibrating an infraredapparatus of the blood gas analyzer type, a device of the nature used insurgical operating rooms to measure a patient's breath gasses. Thiscalibration is achieved with known standard elements which havepredetermined numeric values of radiation, reflection, or absorption.The Apperson apparatus appears however to be only distally related tothe presentation of artificially colored images in a system havinginfrared input capability as in the present invention.

The invention of P. G. Morse in U.S. Pat. No. 4,965,448 is also ofgeneral background interest with respect to the present invention in thesense that it discloses use of a calibration standard in an infrareddetector system. The Morse apparatus also appears however to be onlydistally related to the presentation of artificially colored images in asystem having infrared input capability as in the present invention.

The invention of J. B. Sampsell et al. in U.S. Pat. No. 5,323,002 isalso of general background interest with respect to the presentinvention in the sense that it discloses use of a calibrationarrangement in an optical system. In particular, the Sampsell et al.system uses a spatial light modulator to achieve a desired mix ofdifferent temperature or different color-operated calibration sources.The Sampsell et al. apparatus appears however to also be only distallyrelated to the presentation of artificially colored images in a systemhaving infrared input capability as in the present invention.

The prior patent of an inventor named in the present patent document,U.S. Pat. No. 5,070,239, issued to A. R. Pinkus, is also of backgroundinterest with respect to the present invention. This patent discloses aNIGHT VISION GOGGLE (NVG) testing arrangement which includes an inputsignal source and a NVG output measuring apparatus for evaluating thetested NVG's response to this input signal. The Pinkus apparatus appearshowever to be only distally related to the presentation of artificiallycolored images in a system having infrared input capability as in thepresent invention.

SUMMARY OF THE INVENTION

The present invention achieves artificial coloring in the normallymonochromatic output display of night vision devices. Object colorationaccording to the spectrum or wavelength location of the night visiondevice input data relating to that object is achieved in order to forexample enhance speed and accuracy of operator perception of thedisplayed image.

It is an object of the present invention therefore, to provide anaccurate and convenient night vision device data communicationarrangement.

It is another object of the invention to provide shifting of a nightvision device output image into a broad range of the visible spectrum.

It is another object of the invention to provide a night vision deviceoutput display which is color coded according to some predeterminedconvention.

It is another object of the invention to provide a night vision deviceoutput display that is color coded in a manner easily understood by ahuman user.

It is another object of the invention to provide a color inclusive nightvision device output display which can be accomplished in laboratorysettings with the use of readily available equipment.

It is another object of the invention to provide a night vision devicewhich uses a selectable number of input image wavelength bands infabricating a composite color output image.

It is another object of the invention to provide a night vision devicecolor display which can be fabricated in a relatively small physicalsize.

It is another object of the invention to provide a night vision devicewhich shifts an input image into a selected portion of the visiblespectrum, a portion such as Commission Internationale de l'Eclairage(CIE) color space.

Additional objects and features of the invention will be understood fromthe following description and claims and the accompanying drawings.

These and other objects of the invention are achieved by the method ofcommunicating a composite image, representative of an input scene whichincludes objects generating signatures of differing visible to nearinfrared spectral wavelengths, to a user person comprising the steps of:

dividing said input image into a plurality of component images eachcontaining input scene partial portions received from a selecteddifferent signature spectrum wavelength range of said input image;

displaying each of said component images to said user person as anin-registration different color component of a visible spectrumwavelength resident, composite common output image.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a functional block diagram of apparatus which may be usedto embody the present invention.

FIG. 2 shows an overall perspective physical view of apparatus which maybe used to embody the present invention.

DETAILED DESCRIPTION

FIG. 2 in the drawings shows an overall perspective and physical view ofapparatus which may be used to embody the invention. More precisely,FIG. 2 shows three major components of the preferred embodiment of theinvention, a night vision assembly at 200, a video mixer apparatus at202 and a power supply or energy source, 204, for the other FIG. 2elements. In the FIG. 2 drawing there is specifically shown a pair ofindividual night vision devices 208 and 210 which are coupled as inputsignal sources to the video mixer apparatus 202. These night visiondevices 208 and 210 each include optical assemblies, 212 and 214, andtransducer assemblies 216 and 218 which receive radiant energy inputsignals from the optical assemblies 212 and 214 and generate electricaloutput signals which are communicated to the video mixer apparatus 202.The optical assemblies 212 and 214 each include zoom lense arrays 215and 217 and a pair of optical wavelength filters 219 and 221 whichdivide the radiant energy received from an input scene into twocomponent images of differing wave-length range. These wavelength rangesmay be mutually exclusive as to wavelength or alternately may be of asomewhat overlapping nature as is explained in greater detail inconnection with the FIG. 1 drawing below.

In the night vision assembly 200 the night vision devices 208 and 210include image intensifier tube portions indicated at 252 and 254 in FIG.2 and low light level television camera tube elements comprising majorportions of the transducer assemblies 216 and 218. The night visionassembly 200 also includes a night vision device display assembly 220which incorporates a viewing screen 222. According to the presentinvention, the viewing screen 222 is of the color image displaying typeand is capable of communicating images in at least three colors. Theviewing screen 222 may be for example of the three color, red green andblue image component type as is commonly used in the NTSC (NationalTelevision Standards Committee) and other color television systems. Asshown in FIG. 2 the night vision device display assembly 220 is of thesmall physical size that is characteristic of liquid crystal-baseddisplays; cathode ray tube and other types of displays are of courseusable in other arrangement of the invention. Both the night visionassembly 200 and the video mixer apparatus 202 in the FIG. 2 drawing maybe energized from the power supply or energy source 204; alternately oneor both of these components may be of the serf contained or batteryenergized type. The video mixer apparatus 202 in FIG. 2 is used toreceive component or partial images of an input scene from each of nightvision device 208 and night vision device 210 and to combine thesecomponent images into a composite or final color image. The video mixerapparatus 202 as shown in FIG. 2 is of the three color component orthree channel type of video mixer, e.g., of the type used in the NTSCcolor system. As is shown in the FIG. 1 diagram the video mixerapparatus 202 may be arranged to have two of the available threechannels connected to the same source of video input data, i.e., to theoutput of a single night vision device 208 or night vision device 210 inthe disclosed arrangement of the invention. Coaxial cable or otherconductors for communicating the component image video data from thenight vision device 208 or night vision device 210 to the video mixerapparatus 202 are indicated at 244 and 246 in the FIG. 2 drawing. Theseconductors connect to two of the three input ports 230, 232, and 234 ofthe video mixer apparatus 202; the jumper cable 235 connects the inputof one port to the input of another port in order to achieve thedescribed arrangement of one video signal feeding two mixer input ports.The functions performed within the video mixer apparatus 202, especiallya mixer operating in accordance with the NTSC protocol are believed tobe well known in the electrical and electronic art and to thereforerequire no additional explanation.

Individual channel gain controls for the three channels of the videomixer apparatus 202 in FIG. 2 appear at 236, 238 and 240 in the FIG. 2drawing. These controls enable the selection of differing intensities ofthe respective primary colors, such as the red, green and blue colors ofthe NTSC system, in the output display of the system. This selectivityallows user adjustment of the system output colors. An array of outputports for the signals generated in the video mixer apparatus 202 isindicated at 242 in FIG. 2; these signals may include a subcarriersignal, a NTSC coded signal and a composite image video signal forexample. As shown in FIG. 2 the conductor 248 is used to communicate acomposite image video signal from the video mixer apparatus 202 to thenight vision device display assembly 220.

Video mixer equipment is manufactured by a number of suppliers to theelectronic marketplace in addition to the supplier indicated belowherein. In a space and weight considered and product engineeredarrangement of the invention the video mixer apparatus 202 can of coursebe replaced by dedicated hardware or dedicated software in order torealize the invention in an optimum manner. Such dedicated hardware orsoftware can be arranged to emulate the functions of the video mixerapparatus 202 without undue experimentation by persons skilled in theelectronic art. As is suggested by both the separately housed videomixer apparatus 202 and by the brassboard appearance of the supportboard element 250 in the FIG. 2 drawing, the illustrated arrangement ofthe invention is of a laboratory or non product engineered configurationwhich is embodied with the use of off-the-shelf components. Clearly forvehicular or in-the-field or combat area use of the invention, thecomponents shown in FIG. 2 or their specifically tailored equivalentscan be contained within a single housing, reduced in volume and possiblyweight, ruggedized, and otherwise made more suitable for non laboratorydeployment.

The FIG. 2 apparatus and the following FIG. 1 described details of thisapparatus can perhaps be better appreciated by considering briefly thecurrent state of the night vision device art and possible areas ofimprovement to this art. In a conventional microchannel-based nightvision goggle device, near-infrared (IR) photons (of 650 to 1000nanometers wavelength) are converted to electrons, amplified, and thenusing a phosphor screen, converted into visible green imagery that isviewed by an observer, thereby allowing night vision. Generation 3 nightvision goggles (NVGs) therefore present such a monochromatic,shades-of-green image to the user.

Investigation and experience have shown that an increase in the level ofuser visual performance may be realized with the introduction of colorcoding to this environment Since NVGs amplify near-infrared energy ofthis 650 to 1000 nanometers wavelength and human color vision issensitive to energy in the 400 to 770 nanometers of wavelength range,the addition of color to the output display of a night vision device,when accomplished according to the herein disclosed algorithm may beconsidered to be a mapping of objects from one region of the spectrum toanother region and to thereby result in a synthetic-color scenerendition. In both subjective and objective terms, the presentintroduction of synthetic-color imagery to the night vision device artis believed to provide significant increases in user visual performance.

Conventional night vision devices (e.g., night vision goggles) thereforeprovide an observer with intensified, monochromatic, shades-of-greenimages. The present invention provides an alternative and moreinformative output display for an image-intensified system by addingcolor, according to specific relationships with wavelengths included inthe input image, to the observer's input from the system. The presentinvention combines a spectral filter, lens, and for example amicrochannel plate type image intensifier tube that is optically coupled(via a tapered fiber optic bundle) to a charge coupled device televisioncamera, to form each of two information channels. By wavelengthfiltering or alternately by employing different types of imageintensifier tubes with differing spectral responses (for exampleresponses extended into the blue spectral region), each of theseinformation channels amplifies different spectral regions of thereal-world input image. According to the present invention thesedifferent amplified signals are electronically manipulated and combinedusing a video mixer, the output of which is displayed on a color monitorto the user.

The system of the invention therefore essentially parses the spectrum,then assigns primary colors which are combined to produce amulti-colored output image. This output image is called asynthetic-color image because it maps energy from the invisible to thevisible radiant energy or light, however the system of the inventionarbitrarily assigns (or maps) a visible color, for example, green, toinput image objects which reflect or originate radiant energy of thiswavelength. Generally speaking, this introduction of color-encodingincreases the speed and accuracy of object detection and recognition,when compared to monochromatic systems.

In an optimized configuration of the invention system, certain objectswill be rendered more visible when they are color encoded in this mannerand thereby these objects are made susceptible of quicker detectionand/or recognition by an observer. The system of the invention is alsopreferably arranged to utilize a broad spectrum input which includesboth the visible and infrared spectral regions in order to increasesystem performance. The system of the invention can be packaged for useas a vehicle-mounted sensor system, an arrangement which may be desiredsince the involved apparatus may too heavy for mounting on theobserver's head. In contrast with head-mounted devices such as nightvision goggles, the output images from the present invention can bedisplayed by either a head-down or a visually-coupled display typesystem.

Turning now to the FIG. 1 drawing, there is provided in this drawing anumber of additional details of the present invention and the apparatusshown in the FIG. 2 drawing. In the FIG. 1 drawing the legend numbersare taken from the 100 series of numbers and new numbers in this seriesare assigned to some objects represented in the FIG. 2 drawing; this isaccomplished since FIG. 1 presents these objects in different and morefunctional form. In the FIG. 1 drawing the visible and near-infraredenergy from a night scene, a scene which includes for example thearmored tank 100, is first partitioned into two spectral componentregions-regions such as the wavelength range of 400 to 700 nanometersfor component 1 and 700 to 1000 nanometers for component 2. Thispartitioning is accomplished by the two optical bandpass wavelengthfilters 101 and 116 which may be disposed within or adjacent the nightvision device 208 and night vision device 210 of FIG. 2. The armoredtank 100 is a frequent target for an airborne night vision device and istherefore a realistic representation in the FIG. 1 drawing.

Orthogonality or mutual exclusivity of wavelength ranges is desirablebetween the optical bandpass filter 101 and optical bandpass filter 116in FIG. 1 but is not a requirement for operation of the system.Preferably this mutual exclusivity is such that the two band-passes alsodo not omit any significant range of wavelengths within the selectedoverall range of the system since such a miss could exclude an objecthaving only a signature of that wave-length from the output image of thesystem.. The desired concept in the filtering of input scene radiantenergy is therefore to develop two different component images of theinput scene with these components largely comprising different spectralwavelengths. These components may optionally include some components ofcommon wavelength range especially as such common wavelength componentsare needed to avoid omission or serious attenuation of some intermediatewavelengths.

Relatively large or fast camera lenses as represented at 102 and 118,preferably lenses of f/1.4 size or larger, focus input scene energy ontothe input port face of extended-blue image intensifier tubes 103 and 120in FIG. 1. The output of these tubes is optically coupled by taperedfiber-optic bundle conduits 104 and 122 to the low light levelcharged-coupled device television cameras 105 and 124. The filter(optical bandpass filter 101 and 116), lenses 102 and 118, imageintensifier tubes 103 and 120, and low light level television cameras105 and 124 are all preferably held in a metal fixture which allowsadjustment of height, separation, rotation, and toe-in/toe-out of thetwo subassemblies so that disparate images, caused by parallax forexample, can be made to coincide. The general nature of one arrangementof this fixture can be discerned at 213 in the FIG. 2 drawing.

While this FIG. 2 disclosed arrangement of the invention using twoseparate cameras and manual adjustment for parallax can be used inlaboratory or other embodiments of the invention, it may be moreconvenient to substitute for this FIG. 2 arrangement the use of anactual television camera apparatus, provided of course that such acamera is disposed to have the needed infrared wavelength spectralresponse. Such cameras often employ beam splitter elements and areprovided with the needed careful optical alignment of these and theother optical elements during an initial setup procedure. Once alignedsuch cameras do not then require the parallax correction indicated abovefor a discrete camera arrangement of the invention. Such a televisioncamera embodiment of the invention, when provided with three differentoptical bandpass filters, corresponding to the filters 101 and 116herein, as part of their internal optical system, will of course supplythree optical image component signals relating to the input image ratherthan the two component signals disclosed herein.

The outputs of the two cameras 105 and 124 in the FIG. 1 embodiment ofthe invention are fed to the green, red, and blue inputs 107, 126 and128 of the video mixer 106. The mixer is equipped with three loopingvideo inputs via appropriate connectors. One of these looping inputs isshown in use by way of the cable 235 in order to join the red and bluesignal channels in the FIG. 2 drawing. In the video mixer 106 camerainputs are processed through parallel video amplifiers and routed to theinputs of a video broadcasting industry standardized NTSC encodercircuit. Each video amplifier's gain is controlled by a 10-turnpotentiometer, the potentiometers indicated at 108, 130 and 132 in FIG.2. A video sync generator within the video mixer 106, as indicated at109 in FIG. 1, is controlled by an internal crystal oscillator. The NTSCencoder is tied internally to the video sync generator.

The video sync generator produces composite sync and continuous colorsubcarrier signals, signals that are brought out via BNC connectors togen-lock camera one and camera two, i.e., the FIG. 1 television camera105 and television camera 124, the cameras which correspond to the FIG.2 night vision device 208 and night vision device 210. The video mixer106 may be self-contained and operate on a 12V DC power source 110 toenable use in automobile, airplane, and possibly backpack situations.

The function of the video mixer may be viewed as moving thesynthetic-color mapping of the invention within CIE color space bycombining different amounts of the red green and blue primary colors.These signals can be combined by addition or by subtraction with the useof different primary colors as are known in the optical art.

The FIG. 1 apparatus also provides for a permanent recording of thesynthetic-color rendition of an input scene via for example a super-VHStape recorder 111. Such recording provides for subsequent laboratoryevaluations of system performance in response to varying inputconditions. The user or evaluator can monitor the data collection usinga small, portable, color LCD television receiver as is represented at112 in FIG. 1 and also by night vision device display assembly 220 inFIG. 2. Laboratory and field imagery can also be displayed on a larger,standard sized TV display when for example a group of observersparticipate in an evaluation. The system as described is capable ofproviding output images containing at least blue, green, yellow, orange,red, brown and black color components.

The components of the FIG. 1 and FIG. 2 embodiment of the invention areall of a standard and readily available in the art nature. In theinterest of the most complete disclosure of the invention possiblehowever the following list of identities and commercial sources for theFIG. 1 and FIG. 2 components is included herein.

Optical bandpass filters 101, 116: Corion LS-650,RS 812, Corion USA,Holliston, Ma.

Camera lens 102: Sony 16-64 millimeter zoom, Sony Corporation, Japan.

Extended blue image intensifier tube 103: ITT Corporation, Roanoak, Va.

Fiber optic bundle conduit 104: Electro-Optical ServicesInc.,Charlottesville, Va.

Television camera 105: Sony XC-77, Sony Corporation, Japan.

S-VHS tape recorder 111: Panasonic S-VHS, AG-7400, PanasonicCorporation, Japan.

Television monitor 112,220: Sharp model 4m-T30u, Sharp Corporation, USA.

Optical bandpass filter 116: LL-650-R-V400, Corion USA, Holliston, Ma.

Video mixer apparatus 202: OEI 225, OEI Incorporated, Tuscon Az.

Power supply or energy source 204: Portable power station, Smart ChargeInc.

As shown in the FIG. 1 and FIG. 2 drawings, the system of presentinvention uses the output of the two cameras 105 and 124 or night visiondevice 208 and night vision device 210 to supply data to the three inputports of the video mixer 106 202. A parallel connection of the red andblue inputs of the video mixer 106 202, as represented at 126 and 235 inFIG. 1 and FIG. 2 respectively, is used to accomplish this two to threeport input change in the preferred embodiment of the invention. Clearlythis is not the only possible configuration of the invention since forexample other parallel connections such as green and red are possible inthe FIG. 1 arrangement of the invention. In addition, with the use ofthree different input spectrum filters in lieu of the two shown at 101and 116, three different cameras each feeding its own input of the videomixer 106 can also be employed. Such embodiment of the inventioninvolves the added complexity of optically aligning an additional cameraand its input spectrum filter with two other such camera and filtercombinations but is capable of providing added and possibly desirableresolution of the input spectrum.

In a similar manner, systems according to the present invention may bearranged to use a color display that is limited to two primary colorsalong with a two input video mixer. Systems according to the inventionmay also be assembled to employ different color pairings in a threeprimary color display. As suggested above synthetic colors may also beaccomplished with use of either additive or subtractive primary colorarrangements. In fact, it is within the spirit of the invention toemploy any partition of an input scene into spectral band components andto feed any combination of primary colors with signals representingthese spectral band components. It is also considered within the spiritof the invention to vary the proportions of primary colors in suchcombinations.

The invention may also be arranged to employ several different mappingconfigurations, each one optimized for a different type of mission. Forexample an aircraft mission may comprise an ingress to the target phase;a ground target acquisition and destruction phase and an egress from thetarget phase. For such a mission the instant invention could be used toprovide one mapping scheme, which optimizes the presentation of terrainfeatures, for use in the ingress and egress mission phases and anothermapping scheme, which emphasizes the target and its environmentfeatures, for use in the acquisition and destruction phases. In such anarrangement of the invention electronic switching and proportion controlof primary color mixing can be employed.

Use of the present invention equipment or any night vision equipment inthe cockpit of an aircraft imposes limitation as to the type ofillumination which may be used in that cockpit--if interference betweencockpit lighting and the night vision device is to be avoided. For thisreason, modem day military combat aircraft cockpit illumination andinstrument illumination avoids the use of incandescent, fluorescent andother wide spectrum light sources and favors the use of night visiondevice-compatible, limited spectrum, illumination sources. The cockpitlighting in such aircraft is usually therefore restricted to the visibleregion below 650 nanometers of wavelength while the spectral sensitivityof night vision goggles is usually limited to the near-IR region above650 nanometers of wavelength. Additional details regarding the desiredrelationship between night vision device and cockpit lighting spectralranges is provided in our copending and commonly assigned patentdocument "NIGHT VISION DEVICE AUTOMATED SPECTRAL RESPONSEDETERMINATION", Ser. No. 08/498,499, which is hereby incorporated byreference herein. FIG. 4 of this document shows a graphicalrepresentation of a compatible relationship between night vision devicespectral response and cockpit lighting spectral output.

Where the system of the present invention has no lighting compatibilityrequirements of this nature (for example, where it employs externallylocated sensors with respect to the cockpit or other IR-emitting lightsources) then a much larger spectral range which includes both visibleand near- IR energy can be partitioned before mapping to the primarycolors. This arrangement appears to allow for a higher performancesynthetic color system than one having a more restricted spectral range.Such a synthetic color system is desirable for use withexternally-mounted scene sensors or cameras, cameras mounted in the noseof an aircraft for example. Camera weight and size are also lessrestrictive in this mounting arrangement.

When used as an experimental or laboratory apparatus the presentinvention allows the evaluation of different mapping schema as to theireffectiveness in enhancing an observer's visual performance in groundsite detection and recognition studies for example. This evaluation canof course also be made relative to the standard green night visiondevice imagery. If significant improvements are realized by theintroduction of the present intensified, color-encoded imagery as nowappears likely, the development of color-encoded head-mounted systems,similar in size, spectral range and use, to today's night vision gogglesand other improvements to the fundamental concept of the invention canbe justified.

The optical components shown in FIG. 1 and FIG. 2 may be physicallymounted on an optical bench, or any other reasonably stable mechanicalplatform. In a product-engineered embodiment of the invention thesecomponents may of course be disposed on or within some speciallydesigned rigid structure. An operational equipment or product engineeredembodiment of the invention can be made to be relatively compact,lightweight, and serf-contained in nature so it can be used in the fieldas ground or airborne equipment. When used as an operational militaryapparatus or as a law enforcement apparatus for examples, the presentinvention can employ either a head-down or a visually coupled to theuser's eyes type of display system. While the apparatus and methodherein described constitute a preferred embodiment of the invention, itis to be understood that the invention is not limited to this preciseform of apparatus or method and that changes may be made therein withoutdeparting from the scope of the invention which is defined in theappended claims.

What is claimed is:
 1. Night vision display apparatus for communicatingvisible to infrared spectrum-resident viewed scene input data to a userperson as color-contrasted output images, said apparatus comprising thecombination of:means for dividing an image representing said viewedscene input data into a plurality of component images each comprisinginput scene partial images of a selected different spectrum rangelocation; means for displaying said component images as anin-registration different color component of a spectrumwavelength-shifted, visible spectrum wavelength-resident, compositecommon output image.
 2. The night vision display apparatus of claim 1wherein said component images comprise mutually exclusive wavelengthrange portions of said visible to near infrared spectrum-resident viewedscene input data.
 3. The night vision display apparatus of claim 2wherein said component images are two in number.
 4. The night visiondisplay apparatus of claim 1 wherein said means for dividing said inputimage into a plurality of component images comprises wavelengthsegregated inherent response characteristics in optical elements of saidapparatus.
 5. The night vision display apparatus of claim 1 wherein saidmeans for dividing said input image into a plurality of component imagescomprises:a plurality of radiant energy bandpass filter elements; and aplurality of radiant energy signal to video electrical signal transducermembers each having a radiant energy input port connected with a radiantenergy output of one of said bandpass filter elements.
 6. The nightvision display apparatus of claim 5 wherein said means for dividing saidinput image into a plurality of component images further comprises imageintensifier means disposed intermediate each of said radiant energybandpass filter elements and an associated radiant energy signal tovideo electrical signal transducer member.
 7. The night vision displayapparatus of claim 6 wherein:said image intensifier means comprises anextended-blue image intensifier tube member; said radiant energy signalto video electrical signal transducer members each comprise a chargecoupled device low light level television camera member; and whereinsaid apparatus further includes: tapered fiber-optic bundle meansdisposed intermediate said extended-blue image intensifier tube memberand each said charge coupled device low light level television cameramember for conveying said component images therebetween.
 8. The nightvision display apparatus of claim 5 wherein said means for displayingsaid component images further comprises:video mixer electrical circuitmeans for converting each of said component images into a color-relatedcomponent of said composite common output image; and color coded signalresponsive means for visually communicating said composite common outputimage as a color image to said user person.
 9. The method ofcommunicating a composite image, representative of an input scene whichincludes objects generating signatures of differing visible to nearinfrared spectral wavelengths, to a user person comprising the stepsof:dividing said input image into a plurality of component images eachcontaining input scene partial portions received from a selecteddifferent signature spectrum wavelength range of said input image; anddisplaying each of said component images to said user person as anin-registration different color component of a visible spectrumwavelength resident, composite common output image.
 10. The method ofclaim 9 wherein said input image comprises a near infrared spectralrange limited night vision device-collected image.
 11. The method ofclaim 9 wherein said input image components are two in number.
 12. Themethod of claim 9 wherein said dividing step includes communicating saidinput image to a plurality of radiant energy signal to video electricalsignal transducer members via a plurality of radiant energy bandpassfilter elements.
 13. The method of claim 9 wherein said displaying stepincludes combining said input image components in a video mixerelectrical circuit.
 14. The method of claim 13 wherein said combiningstep includes one of the concepts of signal addition and synchronizationsignal generation in accordance with National Television SystemCommittee (NTSC) standards.
 15. The method of displaying the output of anight vision device to a user person comprising the steps of;dividing anear infrared spectrum input image received by said night vision deviceinto a plurality of component images each inclusive of input imageobjects residing in a selected different near infrared spectrum band;shifting a wavelength characteristic of each said selected differentnear infrared spectrum band into a different color portion of thevisible spectrum wavelength band to form color components of an outputimage of said night vision device; and combining said color componentsof an output image into a composite night vision device output image.16. The method of claim 15 wherein said shifting step includesconverting said near infrared spectrum input image received by saidnight vision device into an image within Commission Internationale del'Eclairage (CIE) color space.
 17. The method of claim 15 wherein saidshifting step includes converting said near infrared spectrum inputimage received by said night vision device into input a plurality ofoptical wavelength-segregated electrical signals.
 18. The method ofclaim 17 wherein said combining step includes mixing said electricalsignals and mixing color components of said composite night visiondevice output image.